(1) Field of the Invention
The present invention relates to a voice band splitting scrambler or, in other words, a secret speech apparatus based on a band splitting and band relocating system. Particularly, the present invention relates to a band splitting scramlber (hereinafter, voice scrambler) having a constitution for collectively carrying out a spectrum inverting process of respective band-split channels to realize a simplification of the hardware.
(2) Description of the Related Arts
As a voice scrambler for realizing scrambled voice communications, an apparatus utilizing a band splitting and band relocation system is in practical use. This apparatus divides a speech frequency band into equal parts and relocates the divided parts. When relocating, the apparatus inverts and shifts predetermined bands.
As a conventional voice scrambler, the HW13 of the MARCONI Co. is known and disclosed in "Explanation of Scrambled Voice Apparatus", Suurikagaku (mathematical science), Dec., 1975.
This conventional apparatus has a disadvantage of a large amount of hardware or a construction containing too many elements, because the spectrum inverting process and the band relocating process of the split bands are carried out by separate elements, as later described in more detail with reference to the drawings.